Automatic machine tool

ABSTRACT

An automatic machine tool includes a head having a rotatable spindle and a head-mounted motor for directly driving the spindle. The head is slidably mounted on a main housing by means of a pair of parallel dovetail engagements, the position of one dovetail track member being selectively adjustable transversely along the housing. A main cam inside the housing translates a cam follower secured directly to the head to slide the head in opposition to a bias force exerted against the head by a fluidoperated piston. De-Actuation of the piston permits translation of the head to an extreme position, providing front access to an opening in the housing which renders the cam accessible. Secondary cams are secured to the same shaft which drives the main cam and actuate control switches as the shaft rotates.

limited States Patent Leacock M lMarch 13, 1973 [541 AUTOMATIC MACHINETOOL 2,472,744 6/1949 Esson ..408/130 [76] Inventor: Ronald Leacock 4719Fielder St 2,506,958 5 1950 Hallenbeck ..308/3 A Tampa 3361 1 PrimaryExaminer-Gerald A. Dost [22] Filed: Dec. 22, 1970 Attorney-Howard L.Rose Appl. No.: 100,714

US. Cl. ..408/44, 408/71, 408/129 Int. Cl. ..B23b 39/20 Field ofSearch....74/55; 29/38 C; 408/3, 4344,

s-mrmu i STATION-'2 STPCHDN [57] ABSTRACT An automatic machine toolincludes a head having a rotatable spindle and a head-mounted motor fordirectly driving the spindle. The head is slidably mounted on a mainhousing by means of a pair of parallel dovetail engagements, theposition of one dovetail track member being selectively adjustabletransversely along the housing. A main cam inside the housing translatesa cam follower secured directly to the head to slide the head inopposition to a bias force exerted against the head by a fluid-operatedpiston. De-Actuation of the piston permits translation of the head to anextreme position, providing from access to an opening in the housingwhich renders the cam accessible. Secondary cams are secured to the sameshaft which drives the main cam and actuate control switches as theshaft rotates.

6 Claims, 7 Drawing Figures STAHON STAUON srrmuu PATENHTUHARMIQB3,720,475

sum 10F z STAT ON STA'TiON-Z STFYUON smnuu \NVENTDR RUNHLD LEACOCKORNEYS 1 AUTOMATIC MACHINE TOOL BACKGROUND OF THE INVENTION The presentinvention relates to automatic machine tools of the type whereinsequential operations may be performed on a workpiece at different workstations. More particularly, the presentinvention is concerned with animproved tool attachment head and operation thereof in an automaticmachine tool assembly.

U. S. Pat. No. 3,398,608 to Redmer discloses an automatic machine toolrepresentative of the type over which the present invention provides animprovement. Redmer discloses a pair of vertical support posts extendingfrom the top of a housing and slidably engaging a machine toolattachment head. The head includes a rotatable spindle which is drivenby a V-belt from a motor mounted on the housing. The head is raised orlowered relative to a translatable work table mounted on the front ofthe housing. Raising and lowering of the head is effected by a verticaldraw bar which is driven by a cam follower which in turn is driven by acam. The cam is secured to a rotatable shaft which is linked to acountershaft having secondary cams secured thereto. The secondary camsactuate switches to effect various control functions for the overallmechanism.

There are a number of disadvantages associated with the Redmer machinetool. One disadvantage relates to the V-belt spindle drive;specifically, the V-belt tends to produce chatter" in the head byvibrating it in a direction perpendicular to the spindle axis. Vibratoryexcursions of the head of one thirty-second inch are common with thisarrangement and quite unacceptable for precise machining operations. Inaddition, since the head is movable relative to the housing, the beltmust be provided with slack to accommodate the furthest separationbetween the motor shaft and head spindle to prevent pivoting of thespindle. This slack tends to produce slippage of the belt and results inunreliable drive characteristics.

Another disadvantage of Redmers arrangement is the difficulty of accessto the main cam. The configuration of the cam determines the nature ofthe head figurations are desirable. The main cam in Redmer is proximatethe front wall of the main housing but access to the cam is not possiblethrough the front wall due to the presence of the work tableat the frontwall and to the disposition of the draw bar between the wall and cam.Consequently, access to the cam must be had by removing a side or rearwall, both being relatively remote from the cam and neither providingsufficient access needed to loosen the cam from its shaft for easy caminterchangeability. 1

Still another disadvantage of the Redmer machine tool resides in therelative complexity of the cam drive movement; for different operations,different cam conarrangement. Redmer employs a clutch-type cam drivemotor which, through a multiple gear arrangement, rotates a main shaftto which the main cam is secured. Experience has shown this arrangementto require frequent maintenance, because'of the tendency of the clutchto slip on the upward stroke. This slippage causes the cam to rotatefaster than the cam follower, draw bar and head can follow, and the headis effectively disengaged from the cam drive. The bias spring then tendsto snap the head back up, a feature which is disadvantageous in itself.Often, instead of snapping up,

however, the head support posts tend to stick in their bushings, causingerratic head movement.

Additional complexity is provided by the necessity to interpose a drawbar between the cam follower and attachment head. Still furthercomplexity is introduced by using further gearing to a countershaft torotate the secondary cams.

Yet another disadvantage with the Redmer arrangement concerns its lackof flexibility in orientation. Specifically, the Redmer head is designedfor vertical movement, thereby limiting the types of machiningoperations it can perform.

It is therefore an object of the present invention to provide anautomatic machine tool arrangement which is devoid of the aforementioneddisadvantages.

One specific object of the present invention is to provide an automaticmachine tool of the type described wherein the chatter problem in thehead is eliminated. More particularly, it is an object of the presentinvention to provide a spindle drive which does not vibrate or pivot themachine tool head.

Another object of the present invention is to provide a cam-operatedautomatic machine tool in which access to the cam is had through a frontpanel opening proximate the cam position.

Still another object of the present invention is to provide a simpledrive arrangement for the main cam and secondary cams in a cam-operatedautomatic machine tool.

Still another object of the present invention is to provide an automaticmachine tool which is capable of efficient operation no matter how it isoriented.

SUMMARY OF THE INVENTION According to the present invention, directdrive is provided for the spindle by a head-mounted motor. In addition,the head is slidably engaged by the housing by means of a pair ofdovetail tracks, the head being biased by a fluid-operated pistonagainst the action of a cam engaging a cam follower directly connectedto the head. De-actuation of the piston permits displacement of the headto an extreme position which renders accessible an opening in the frontpanel of the housing through which the cam may be easily loosened. Asingle drive shaft is provided for the main cam and secondary cams andis driven by a motor through a relatively simple gear arrangement.

BRIEF DESCRIPTION OF THE DRAWINGS The above and still further objects,features and advantages of the present invention will become apparentupon consideration of the following detailed description of specificembodiments thereof, especially when taken in conjunction with theaccompanying drawings, wherein:

FIG. I is a top view in plan of a multi-station automatic machine toolassembly utilizing the principles of FIG. 6 is a front view in elevationof another automatic machine tool attachment employed at a station inFIG. 1', and

FIG. 7 is a view in section taken along lines 7-7 of FIG. 6.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring specifically to FIGS. 1and 2, an automatic machine tool assembly 10 is arranged toautomatically perform a series of machining operations. A controlhousing 11 for the assembly includes a horizontal hexagonal surface 13above which is supported a circular indexing table 15. Six workpieceholding elements or chucks 17 are disposed on table 15, 60 apart and atequal radial distances from the center of the table. Six operationstations are defined at the six sides, respectively, of surface 13.Station 1 is an automatic loading station at which the workpiece to bemachined is automatically loaded and secured to a chuck 17. Stations 2,3, 4, 5 include automatic machine tools, according to the principles ofthe present invention, which perform various machining operations on theworkpiece. Station 6 effects automatic unloading of the finishedworkpiece from the indexing table. The indexing table is arranged torotate in 60 steps to present the workpiece in proper alignment with themachine tool, loading or unloading mechanism at each station.

As an example, assume the assembly of FIGS. 1 and 2 is arranged to drilla bore having an undercut into a workpiece and then provide a crossdrilled hole perpendicular to the bore. After being loaded at station 1,the workpiece is rough-bored at station 2. The bore is finished atstation 3 and the undercut is supplied at station 4. The cross-drilloperation is effected at station 5 as indicated by fact that the machinetool head at station 5 is oriented perpendicular to the head at stations2 and 3. The workpiece is automatically unloaded at station 6.

Referring to FIGS. 3, 4 and 5 there is illustrated an automatic machinetool 20 of the type employed in assembly 10 of FIGS. 1 and 2. Machinetool 20 includes a main housing 21 and a machine tool attachment or head23 which is movable relative to the main housing. Mounted interiorly ofmain housing 21 is a motor 25 which drives a set of gears in a speedreduction gear box 27. Gear box 27 is supported within main housing 21by any suitable members generally designated by the numerals 29, 31. Ashaft 33 is driven by gear box 27 and extends perpendicularly toward thefront wall 35 of main housing 21. Shaft 33 is rotatably supported insupport member 31 by means of bearings 39.

A main cam 40 is eccentrically secured-to the end of shaft 33 proximatefront wall 35 by means of nut 37. An alignment pin 38 mates with analignment aperture on standard screw machine cams to assure properrotational position of the cam when it is installed and to provide apositive driving element for the cam. A group of smaller secondary earns41 are also eccentrically secured to shaft 33 behind the main cam (tothe left in FIG. 3) and are arranged to sequentially actuate respectiveswitches 43 at different portions of the rotation cycle of shaft 33.Switches 43 are operatively connected to respective control valves 45which form part of pneumatic or hydraulic circuits employed to controlthe various automatic functions performed by assembly 10. The manner inwhich such circuits operate depends upon the particular operationalsequences to be performed, such circuits being well-known as exemplifiedby the aforementioned U. S. Patent to Redmer. Of course, switches 43 canoperate electrical circuits if 5 electrical controls are employed.

Front wall 35 of main housing 21, which is vertical in FIG. 3 althoughit is not necessarily so positioned, has secured thereto a pair ofvertically extending spaced blocks 47, 49. A vertically extendingchannel is formed in each block 47, 49 and is arranged to serve as thefemale portion of a slidable dovetail engagement with a suitable malemember 51, 53 projecting from rear wall 55 of machine tool attachment23. Block 49 is either integral with or fixedly secured to front wall 35by means of bolts or the like. Block 47 is slidably mounted fortransverse movement on wall 35 by means of bolts 55 in tracks 57; inthis manner the spacing between block 47,49 is adjustable to accommodatevariations in spacing between member 51, 53 of different machine toolattachments 23. As each interchangeable machine tool attachment isattached to main housing 21, the lateral position of block 47 isadjusted and tightened to pre-load (i.e.-exert lateral forces upon) themale members 51,53 of the dove-tail engagement.

A cam follower 57 is secured to rear wall 55 of machine tool attachment23 and extends into main housing 21 through a vertically extending slot59 defined through front wall 35 of the main housing. Cam follower 57 isengaged by the periphery of main cam 40 and is therefore displaced inslot 59 in accordance with the rotational position of shaft 33.

A selectively actuable hydraulic cylinder 61 includes a shaft secured torear wall 55 of machine tool attachment 23. During operation of themachine tool, cylinder 61 is actuated to bias attachment 23 upwardly,thereby urging cam follower 57 into engagement with the periphery ofmain cam 40. The main cam thus drives the cam follower in opposition tothe bias action of cylinder 61 and causes the machine tool attachment toslide relative to the main housing via the dovetail engagement. Cylinder61 acts to prevent diving," which is the sudden drop of attachment 23upon breakthrough of the tool through the workpiece. In this context,cylinder 61 provides a positive depth control for the head 23.

When cylinder 61 is de-actuated machine tool attachment 23 slides to itslowermost position, rendering accessible a removable plug 63 covering anaccess opening in front wall 35 of the main housing. The removable plugcan be pulled out to provide access to main cam 40, and particularly tonut 37. Removal of nut 37 is thus simply accomplished for purposes ofchanging main cams. The cam itself can be slid off shaft 33 and droppedto a position which is accessible from on the head. The motor isarranged to provide direct rotary drive to a spindle 67 arranged to holdthe tool bit. This direct drive arrangement avoids the chatter inherentin the V-belt drive arrangement of the aforementioned Redmer patentwherein the drive motor is secured to the main housing rather than tothe head.

The orientation illustrated in FIGS. 3, 4, 5 for automatic machine toolis by no means exclusive. For example, if machine tool 20, as viewed inFIG. 3, were rotated 90 counterclockwise, spindle 67 would be disposedhorizontally rather than vertically and attachment 23 would be slidablehorizontally rather than vertically. This orientation is illustratedspecifically at station 5 in FIG. 1. In any orientation, the main cam 40drives cam follower 57 and attachment 23 in opposition to the bias forceeffected by hydraulic cylinder 61. The dovetail engagement providesreliable slidable engagement for all orientations, and there is no unduestress placed on any element of the machine tool as the orientation isvaried.

A variation of the embodiment of FIGS. 3, 4 and Sis illustrated in FIGS.6 and 7 wherein machine tool attachment 70 is arranged to performing amilling operation. Attachment or head 70 has identical components tohead 20 and also includes a right angle gear box 71, driven by spindle67, and which rotates a shaft 73 about an axis perpendicular to that ofspindle 67. A support 75 depends from the head and is provided with ahole in which shaft 73 is journaled. A milling cutter 77 is mounted onshaft 73 to rotate therewith. If desired a fixed shaft 79 may be securedbetween support member 75 and the main head body to provide additionalstabilization for the milling cutter.

The advantageous features of the present invention may now be summarizedbriefly:

l. Spindle drive motor 65 is mounted on the head 23 and provides directdrive for spindle 67. This eliminates the chatter and spindle pivotingproblems inherent in the prior art.

2. Cam shaft 33 directly drives both the main cam 40 and secondary cams41, and is itself driven from a motor and a simple speed reduction geararrangement.

3. The dovetail engagement between head 23 and main housing 21 permitssmooth motion of the head for any head orientation. The adjustabledovetail track spacing permits lateral loading for interchangeable heads23.

4. Simple access is had to the main cam 40 via plug 63 by simply movingthe head to an extreme position.

5. Cam follower 57 is secured directly to the head 23 rather thanindirectly driving the head through a draw bar or similar arrangement.The resulting head drive is simpler and more reliable.

While I have described and illustrated specific-embodiments of myinvention, it will be clear that variations of the details ofconstruction which are specifically illustrated and described may beresorted to without departing from the true spirit and scope of theinvention as defined in the appended claims.

Iclaim:

1. An automatic machine tool assembly comprising:

an indexing work table arranged to rotate in equal angular steps aplurality of stationary work stations positioned along the periphery ofsaid work table at locations spaced by said equal angular steps;

a plurality of workpiece holding elements mounted on said work table atrespective locations spaced at said equal angular steps;

a plurality of machine tools, each located at a different work stationsuch that said workpiece holding elements align with said machine toolsat index positions of said work table;

wherein at least two of said machine tools each include:

a main housing including at least one wall having a slot defined thereinwhich extends longitudinally towards said work table;

a machine tool carriage;

engagement means for mounting said machine tool carriage on said wall ofsaid main housing to permit slidable motion of said machine toolcarriage along said wall;

means for biasing said machine tool carriage in a direction away fromsaid work table and along said wall;

a main eccentric cam mounted within said housing for rotatable motionabout an axis perpendicular to said wall;

a cam drive motor located within said housing for rotating said main camabout said axis;

a cam follower secured directly to said machine tool carriage andextending through said slot to the interior of said housing intoengagement with said main cam such that said main cam opposes motion ofsaid cam follower away from said work table, said cam follower beingresponsive to rotation of said main cam for effecting slidable motion ofsaid machine tool carriage along said wall.

2, The automatic machine tool assembly according to claim 1 wherein saidmachine tools each further include: a spindle rotatably mounted on saidmachine tool carriage; and a motor mounted on said machine tool carriagefor rotatably driving said spindle.

3. The automatic machine tool assembly according to claim 2 wherein saidmachine tools each further comprise:

a shaft extending above said axis and rotatable by said earn drive motorto in turn drive said main cam;

a plurality of secondary cams secured to said shaft;

a plurality of switches arranged adjacent said shaft for cyclicactuation by respective secondary cams during rotation of said shaft,said switches being arranged to eontrol operational sequences in saidmachine tool.

4. The automatic machine tool assembly according to claim 1 wherein saidengagement means is a dovetail engagement comprising: a pair of malemembers projecting from said machine tool carriage and extendingparallel to one another and to said wall; and a pair of female membersextending along said wall and com figured to receive said male membersin slidable engagement; wherein at least one of said female members isselectively translatable along said wall in a direction transverse tothe slidable direction of said carriage,

5. The automatic machine tool assembly according t claim 1 whe e n imeans for bi ing mprises a fluid pressure operated drive memberselectively actuable to bia i ma hine t ol carriage away from aid worktabl 6. The automatic machine tool assembly according to claim 1 furthercomprising an access opening in said wall of said main housing which isaccessible upon deactuation of said fluid pressure operated drive memberand translation of said machine tool carriage to its ex- 5 tremeposition in the direction toward said work table.

1. An automatic machine tool assembly comprising: an indexing work tablearranged to rotate in equal angular steps; a plurality of stationarywork stations positioned along the periphery of said work table atlocations spaced by said equal angular steps; a plurality of workpieceholding elements mounted on said work table at respective locationsspaced at said equal angular steps; a plurality of machine tools, eachlocated at a different work station such that said workpiece holdingelements align with said machine tools at index positions of said worktable; wherein at least two of said machine tools each include: a mainhousing including at least one wall having a slot defined therein whichextends longitudinally towards said work table; a machine tool carriage;engagement means for mounting said machine tool carriage on said wall ofsaid main housing to permit slidable motion of said machine toolcarriage along said wall; means for biasing said machine tool carriagein a direction away from said work table and along said wall; a maineccentric cam mounted within said housing for rotatable motion about anaxis perpendicular to said wall; a cam drive motor located within saidhousing for rotating said main cam about said axis; a cam followersecured directly to said machine tool carriage and extending throughsaid slot to the interior of said housing into engagement with said maincam such that said main cam opposes motion of said cam follower awayfrom said work table, said cam follower being responsive to rotation ofsaid main cam for effecting slidable motion of said machine toolcarriage along said wall.
 1. An automatic machine tool assemblycomprising: an indexing work table arranged to rotate in equal angularsteps; a plurality of stationary work stations positioned along theperiphery of said work table at locations spaced by said equal angularsteps; a plurality of workpiece holding elements mounted on said worktable at respective locations spaced at said equal angular steps; aplurality of machine tools, each located at a different work stationsuch that said workpiece holding elements align with said machine toolsat index positions of said work table; wherein at least two of saidmachine tools each include: a main housing including at least one wallhaving a slot defined therein which extends longitudinally towards saidwork table; a machine tool carriage; engagement means for mounting saidmachine tool carriage on said wall of said main housing to permitslidable motion of said machine tool carriage along said wall; means forbiasing said machine tool carriage in a direction away from said worktable and along said wall; a main eccentric cam mounted within saidhousing for rotatable motion about an axis perpendicular to said wall; acam drive motor located within said housing for rotating said main camabout said axis; a cam follower secured directly to said machine toolcarriage and extending through said slot to the interior of said housinginto engagement with said main cam such that said main cam opposesmotion of said cam follower away from said work table, said cam followerbeing responsive to rotation of said main cam for effecting slidablemotion of said machine tool carriage along said wall.
 2. The automaticmachine tool assembly according to claim 1 wherein said machine toolseach further include: a spindle rotatably mounted on said machine toolcarriage; and a motor mounted on said machine tool carriage forrotatably driving said spindle.
 3. The automatic machine tool assemblyaccording to claim 2 wherein said machine tools each further comprise: ashaft extending above said axis and rotatable by said cam Drive motor toin turn drive said main cam; a plurality of secondary cams secured tosaid shaft; a plurality of switches arranged adjacent said shaft forcyclic actuation by respective secondary cams during rotation of saidshaft, said switches being arranged to control operational sequences insaid machine tool.
 4. The automatic machine tool assembly according toclaim 1 wherein said engagement means is a dovetail engagementcomprising: a pair of male members projecting from said machine toolcarriage and extending parallel to one another and to said wall; and apair of female members extending along said wall and configured toreceive said male members in slidable engagement; wherein at least oneof said female members is selectively translatable along said wall in adirection transverse to the slidable direction of said carriage.
 5. Theautomatic machine tool assembly according to claim 1 wherein said meansfor biasing comprises a fluid pressure operated drive member selectivelyactuable to bias said machine tool carriage away from said work table.